Cogeneration Heat Rate Reference

Heat rate, power-to-heat ratio, and efficiency benchmarks for gas-turbine, steam-turbine, and reciprocating-engine cogen configurations.

Heat Rates

Cogeneration / Power Cycle Heat Rate Reference · Heat rate (Btu/kWh) and thermal efficiency for common power + steam supply cycles

Cycle	Primary Mover	Size Range (MW)	Net Heat Rate (Btu/kWh LHV)	Efficiency (%)	PURPA Criteria Met?	Typical CHP Efficiency (%)	Notes
Simple-Cycle Gas Turbine	Frame GT	5-350	9,500-11,200	31-36	Marginal	40-55 (with HRSG)	GE 7F, Siemens SGT6; efficiency rises with firing temp
Combined-Cycle Gas Turbine (1x1)	GT + HRSG + ST	60-400	6,400-7,100	48-53	Yes	75-82	Dry cooling penalizes ~2%; F-class vs H-class 53 vs 60%
Combined-Cycle H-Class	H-class GT	300-600	5,800-6,200	58-62	Yes	80-85	9HA.02 (GE), SGT-9000HL (Siemens)
Aeroderivative GT	LM6000, LMS100	20-100	8,500-8,900	40-44	Yes	65-75	Fast start, peaking and CHP
Recip Gas Engine	Wartsila, Caterpillar	1-20	7,900-8,400	40-48	Yes	75-85	Jenbacher/Wartsila; biogas friendly
Steam Turbine (condensing)	Extraction/cond ST	10-500	9,500-11,000	30-38	Yes	70-80	Process steam extraction; biomass boiler application
Steam Turbine (back-pressure)	Backpressure ST	1-50	4,500-5,500 (effective)	-	Yes	85-90	Refinery captive power; very efficient
Organic Rankine Cycle	ORC	0.1-10	12,000-15,000	18-24	No	60-70	Waste-heat recovery, geothermal, biomass
Supercritical Coal	ST	300-1000	8,500-9,200	40-45	-	-	SC >3625 psi; USC >4500 psi
IGCC Coal+Gas	GT+ST + gasifier	250-600	8,200-8,700	42-47	-	-	Polk, Wabash River
Small Modular Reactor	ST	50-300	10,500-11,500	32-35	-	-	NuScale, BWRX-300
Fuel Cell (SOFC)	SOFC	0.1-50	6,400-7,100	50-60	-	75-85	Bloom, Mitsubishi; CHP applications

HRSG Config

HRSG & Steam-Cycle Configurations

Config	Typical Pressure (psig)	Reheat	Steam Temp (°F)	Incremental eff. (%)	Comment
1-P HRSG unfired	600	No	750	-	Simple; small CHP
2-P HRSG	HP 1,500 / LP 150	No	900/400	+2-3	Industrial CHP with deaerator steam
3-P HRSG Reheat	HP 2,400 / IP 500 / LP 50	Yes	1,050/1,050/400	+3-5	Standard for modern CCGT
HRSG Supplementary Fired	+ 30% duty	Yes	1,050	+ capacity	Boost in winter; efficiency drops ~1 pt
Once-Through HRSG	2,400	Yes	1,100/1,100/400	+1	No steam drum; lighter, faster start

PURPA FERC

PURPA Qualifying Facility (QF) Criteria · 18 CFR 292.205 — Efficiency + useful thermal output tests

Test	Requirement	Formula / Description
Useful Thermal Output	≥5% of total energy output	Q_thermal / (Q_thermal + P_electric)
Operating Standard (oil/gas)	(P_elec + 0.5*Q_thermal) / Q_fuel ≥ 42.5%	PURPA §292.205(a)(2)
Operating Standard (biomass)	(P_elec + 0.5*Q_thermal) / Q_fuel ≥ 42.5%	Same calc; biomass is automatic 'small power' QF ≤80 MW
Topping Cycle	≥5% thermal output from cycle	Applies when thermal follows power generation
Bottoming Cycle	Waste heat → power	Exempt from efficiency criteria

References

Source: Cogeneration_Heat_Rate_Reference_v1.xlsx

© 2026 Inflection Point Engineering, LLC. All rights reserved. The content of this page — including calculation methods, reference data, written analysis, interactive tools, and source code — is the intellectual property of Inflection Point Engineering, LLC and is protected under applicable copyright, trademark, and trade secret laws. Unauthorized reproduction, redistribution, modification, or derivative use in whole or in part is prohibited without prior written consent.

Disclaimer. This material is provided for informational and educational purposes only and does not constitute professional engineering advice. Calculations, reference data, and methodologies are based on published standards and accepted engineering practice but are not a substitute for engineering judgment, site-specific analysis, or review by a licensed Professional Engineer. Inflection Point Engineering, LLC makes no warranties, express or implied, regarding the accuracy, completeness, or fitness for a particular purpose of any content presented here, and shall not be liable for any direct, indirect, incidental, or consequential damages arising from its use. Users assume all risk associated with applying this content to real-world design, operations, or decisions.